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Epsilon Profiling Tools [message #1773591]

Fri, 29 September 2017 18:17

taghreed altamimi

Messages: 184
Registered: October 2014

Senior Member

Hi,

I notice that the execution time in Epsilon profiling always gives integer numbers ,so can i change the format of the execution time to be like 0.1 or 0.2 because i got 0 ms for the small operations .I am assuming that the execution time for such case is between 0-0.5 .

Thanks
Taghreed

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Re: Epsilon Profiling Tools [message #1773626 is a reply to message #1773591]

Sun, 01 October 2017 14:13

Antonio Garcia-Dominguez

Messages: 594
Registered: January 2010
Location: Birmingham, UK

Senior Member

Yes, Epsilon takes times in milliseconds:

https://git.eclipse.org/c/epsilon/org.eclipse.epsilon.git/tree/plugins/org.eclipse.epsilon.profiling/src/org/eclipse/epsilon/profiling/Stopwatch.java#n21

We could take times in nanoseconds, but in practice that doesn't work so well for small tasks:

* The resolution of the timer is OS-dependant (you might not get times at the nanosecond level anyway).
* For very small tasks, anything else going on in your computer will distort the results too much.
* The just-in-time recompilation of the Java runtime will also distort results.

Usually I'd recommend using the Epsilon profiler against larger models rather than trying to measure very small tasks. For that, you would need a proper microbenchmarker (like JMH for Java) that allows you to "warm up" the JIT recompiler.

Do you have access to larger models, or can you at least run the same operation repeatedly a considerable number of times in the same execution of the Epsilon script?

Also, if you really want to do microbenchmarking, you should probably check a few articles on the underlying complexities:

https://shipilev.net/blog/2014/nanotrusting-nanotime/

[Updated on: Sun, 01 October 2017 14:16]

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